OPA622AP BURR-BROWN [Burr-Brown Corporation], OPA622AP Datasheet - Page 14

• Manufacturer Part Number: OPA622AP
• Description: Wide-Bandwidth OPERATIONAL AMPLIFIER
• Manufacturer: BURR-BROWN [Burr-Brown Corporation]

time constants. The elements R and C
current source output and the output buffer form the first
open-loop pole T
the output buffer, combines several small phase-shifting
time constants and delay times. They are distributed through-
out the amplifier and are also present in the feedback loop.
As shown in Figure 10, an increasing R
decreasing open-loop gain. The ratio of the two time con-
stants, T
determines the product G
frequency response.
T
now is to vary G
constant, which is the theoretical condition for optimal and
gain-independent frequency response. Figure 11 summarizes
some optimal flat closed-loop responses and indicates the R
values. It should be noted that the bandwidth remains rela-
tively constant and R
FIGURE 7. Bandwidth vs Output Voltage (Feedback Buffer ).
FIGURE 8. Bandwidth vs Output Voltage (Current-Feedback
C
and T
–10
–15
–20
–25
–10
–15
–20
–25
dB
20
15
10
–5
dB
20
15
10
–5
5
0
5
0
C
D
1.4Vp-p
0.6Vp-p
0.2Vp-p
and T
are fixed by the op amp design. The purpose of R
5.0Vp-p
2.8Vp-p
Amplifier).
®
1M
1M
1.4Vp-p
D
0.6Vp-p
0.2Vp-p
OPA622
G
OL
2.8Vp-p
, of the open-loop frequency response also
C
OL
150
. The signal delay time, T
180
versus G
OG
= G
13
4
+
–
has its highest value (low open-loop
180
10M
+
10
150
10M
OL
Frequency (HZ)
CL
Frequency (HZ)
0.5pF
CL
9
• G
•
to keep the product G
150
2T
CL
T
+1
C
3
D
G
for optimal closed-loop
100M
100M
+1
CL
8
= +2V/V
8
OTA
1k
OG
D,
between the
modelled in
1G
leads to a
1G
OL
• G
3G
3G
OG
OG
CL
14
gain) at low closed-loop gains. Harmonic distortion is also
improved with increased open-loop gain. Figure 12 shows the
OPA622 frequency response at G
R
Slight variation of R
load capacitance. It is possible to achieve optimal pulse
response over a wide range of load capacitances without
overshooting and ringing. As an example, Figure 13 shows a
selection curve for the optimal R
capacitance at a gain (G
THERMAL CONSIDERATIONS
The OPA622 does not require a heat sink for operation in
most environments. A heat sink will, however, reduce the
internal thermal rise, resulting in cooler, more reliable
operation. At extreme temperatures and under full load
conditions, a heat sink is necessary. The internal power
dissipation is given by the equation P
the quiescent power dissipation and P
pation in the output stage due to the load). Although the P
is very low (50mW at V
FIGURE 9. Hybrid Model of a Wideband Op Amp.
FIGURE 10. Open-Loop Gain vs R
OG
to demonstrate its influence on a flat frequency response.
–10
–20
60
50
40
30
20
10
0
10k
+In
4
13
100k
10
R
g
T
m
OG
might be necessary to compensate for
R
CLO
OG
CC
Frequency (Hz)
C
1M
) of +2V/V.
T
g
= 5V), care should be taken
m
R
OG
8
–1
=
CL
OG
3
10M
OG
0
T
–In
= +2V/V and variable
D
D
9
.
value versus the load
DL
= P
27
is the power dissi-
DQ
R
R
2
1
150
100M
V
+ P
OUT
DL
390
, (P
1G
DQ
DQ
is